International Journal of Prosthodontics最新文献

Purpose: To evaluate and compare the fracture mode and strength of monolithic zirconia to veneered zirconia and metal-ceramic full-coverage restorations following artificial aging. The main concern was to test the performance of translucent zirconia in terms of load-bearing capacity.

Materials and methods: Two mandibular first molars were prepared and scanned for their respective groups of full-coverage restorations. 75 full-coverage restorations were fabricated and divided into five groups: two groups for monolithic zirconia, two groups for veneered zirconia, and one group for metal-ceramic. 75 light-cured hybrid composite resin dies were fabricated to serve as abutments. Before cementation, all full-coverage restorations were subjected to accelerated aging. After cementation, all full-coverage restorations were subjected to compressive loading until fracture in an electromechanical universal testing machine. A two-way nested analysis of variance and Tukey test were used to analyze the results with 95% confidence levels.

Results: Monolithic zirconia full-coverage restorations showed the highest mean fracture resistance of 4,201 N, followed by metal-ceramic full-coverage restorations of 3,609.3 N, and the veneered zirconia full-coverage restorations showed the lowest of 2,524.6 N. The main mode of failure was cohesive bulk fracture for the monolithic zirconia group, cohesive/adhesive failure along with infrastructure damage for the veneered zirconia group and cohesive/adhesive failure without infrastructure damage for the metal-ceramic group.

Conclusions: Monolithic zirconia full-coverage restorations showed superior resistance to fracture in comparison to metal-ceramic full-coverage restorations and are highly reliable in terms of load-bearing capacity within the posterior regions of the mouth.

Purpose: To describe the treatment of malpositioned implants in the esthetic area using the angulated welded abutment (AWA) approach together with peri-implant soft tissue surgery.

Materials and methods: A clinical case with extreme buccal angulation of two implants in the anterior maxilla was used to illustrate the AWA technique. After implant impression-taking, digital analysis was used to determine the ideal prosthetic angulation of the abutment and the ideal position of its screw hole in relation to the gingival margin of the adjacent teeth. The AWA was designed in two combinable components that were meant to be welded together. Before the welding process, an angulated screw was included in the abutment. Since the angulated screw was inside the abutment, the screwdriver hole could be designed as narrow as possible and put in an ideal position. After periodontal and peri-implant surgery were carried out, the AWA was applied to the implants.

Results: The AWA allowed correction of the prosthetic axis. Moreover, relocation of the screw hole allowed the gingival tissue to creep over the abutment. In this way, a new esthetic restoration can be placed after the mucogingival surgery.

Conclusion: The excessive misangulation of the implants was efficiently recovered. Further studies are needed to evaluate long-term clinical success, and standardization of this technique is required for routine clinical use. Int J Prosthodont 2023;36:228-232. doi: 10.11607/ijp.759.

Purpose: To assess (1) whether an occlusal splint (OS) or mandibular advancement splint (MAS) allowed better sleep quality and was more comfortable in individuals with sleep bruxism (SB); and (2) the relationship between sleep quality, comfort, and reduction in RMMA related to SB.

Materials and methods: Polysomnographic data from 21 SB subjects (mean ± SD age 25.6 ± 4.5 years) collected in two previous studies were compared. Morning self-reports on sleep quality and comfort of the oral device, polysomnographic data, and RMMA index data from no-device nights were compared to nights using an OS or MAS. The reduction ratio of the RMMA index was calculated for both devices. A responder to the oral device was identified when the RMMA index was less than 2 and when it showed a reduction of at least 50% from the no-device control night.

Results: Self-reports for sleep quality and comfort of the oral device showed a mild advantage of the OS when compared to the MAS (r² = 0.47, r² = 0.32; P ≤ .01). In responders, the MAS induced a greater reduction in the RMMA index (P = .03) than the OS.

Conclusions: In the short term, the comfort of the oral device seemed to influence sleep quality in SB individuals. However, despite the slightly higher degree of comfort offered by the OS, the MAS induced a greater effect on the RMMA index. Int J Prosthodont 2022;36:138-147. doi: 10.11607/ijp.7525.

Purpose: To evaluate the effect of cavity tapering on marginal and internal adaptation of endocrowns fabricated from two different ceramic materials.

Materials and methods: Two mandibular molar model teeth were prepared with two different cavity tapers (5 and 10 degrees). A total of 40 endocrowns (four groups of 10 each) were milled using lithium disilicate and zirconia-reinforced lithium silicate ceramics for each cavity taper. The marginal and internal adaptation of endocrowns were measured by a stereomicroscope (×30) at 18 different points. The data were statistically analyzed using independent t test (P < .05).

Results: A statistically significant difference was shown among the tested groups at 10 degrees of taper (P < .001). At 5 degrees of taper, the difference was insignificant. The greatest internal gap was observed at the pulpal floor in all tested groups.

Conclusion: All materials had clinically acceptable internal and marginal gaps; however, lithium disilicate ceramic had significantly better adaptation at 10 degrees of taper. Int J Prosthodont 2023;36:189-193. doi: 10.11607/ijp.6877.

Purpose: To survey the materials favored by dentists for intraoral repair of cohesive chipping.

Materials and methods: From August 2019 to February 2020, dentists were surveyed to determine the frequency of cohesive chipping experienced within the last 3 months and to identify their preferred approaches for intraoral repair.

Results: Of the participants, 42.5% observed chipping (n = 506). Participants favored the application of roughening devices, silane, and composite resins. Self-etching glass-ceramic primers or hydrofluoric acid were used for ceramic etching.

Conclusion: Dentists apply a variety of materials for intraoral repair of chipping, including materials that are not approved for intraoral use. Int J Prosthodont 2023;36:216-218. doi: 10.11607/ijp.7098.

Purpose: To analyze the clinical performance of two-wing–retained resin-bonded fixed dental prostheses (RBFDPs) after 5 years of clinical use with respect to technical and biologic complications, as well as survival and success rates.

Materials and methods: RBFDPs were fabricated from 3Y-TZP zirconia layered by hand (Lava Frame veneered with Lava Ceram; 3M ESPE) or metal (Remanium Star, Dentaurum; layered with Reflex, Wieland). The primary endpoints were debonding and fracture. The secondary endpoints (marginal integrity, marginal discoloration, abrasion of antagonist dentition, patient satisfaction, Gingival Index, and side effects) were evaluated at baseline and after 5 years. Survival and success rates were calculated using the Kaplan-Meier method. Log-rank test was used to compare the survival and success rates of the different materials.

Results: The mean observation time was 6 years and 10 months. The estimated cumulative success rate after 5 years was 88.9% ± 10% for metal-supported and 33% ± 16% for all-ceramic two-wing RBFDPs. After conversion into one-wing RBFDPs, the survival rate was 100% in both groups. Debonding of one of the two wings was the major complication. One zirconia framework fracture occurred. Metal-based two-wing RBFDPs showed a significantly higher success rate, but lower esthetic evaluation.

Conclusion: Due to a reduction in technical complication rate and less invasiveness, one-wing RBFDPs should be preferred over two-wing RBFDPs whenever possible.

Purpose: To present a minimally invasive treatment approach for the replacement of two missing adjacent teeth with two single-retainer resin-bonded fixed dental prostheses (RBFDPs).

Materials and methods: Two missing adjacent premolars were restored by two RBFDPs with an innovative design of the proximal section. Both RBFDPs were digitally designed and milled from monolithic 3Y-TZP zirconia ceramic using CAD/CAM. Following construction of the anterior RBFDP, a shallow interlock was designed in the area of proximal contact in the same insertion direction as the posterior RBFDP. In this way, different paths of insertion of the RBFDPs could be provided without compromising the proximal hygiene capability.

Results: The presented minimally invasive restorations were successful over 5 years of clinical bservation without any complications.

Conclusion: The presented restoration design secures the transversal position of the RBFDPs while maintaining physiologic tooth mobility. In addition, it allows for varying paths of insertion while improving hygienic conditions. Last, in case of a unilateral debonding of one retainer wing, rebonding might be possible. Int J Prosthodont 2023;36:155-160. doi: 10.11607/ijp.7711.

Purpose: To evaluate the effect of different abutment screw retightening procedures on the screw stability between the abutment and implant.

Materials and methods: External hexagon connection (EHC) and internal trichannel connection (ITC) implants were employed in this study. Each abutment screw was used for the following specific applications (n = 5 for each group): group 0 = abutment was tightened and retightened with a 10-minute interval; group 1 = abutment was tightened and retightened with a 10-minute interval, then loaded for 500,000 cycles; group 2 = abutment was loaded for 83,000 cycles during tightening and retightening, then loaded for 500,000 cycles; group 3 = abutment was loaded for 167,000 cycles during tightening and retightening, then loaded for 500,000 cycles; and group 4 = abutment was loaded for 250,000 cycles during tightening and retightening, then loaded for 500,000 cycles. Both tightening and retightening torques were set at 35 Ncm, and dynamic oblique loading between 0 N and 200 N was applied on the abutment in all groups. The settling values of the abutments after retightening and the abutment removal torque values (RTVs) after testing were measured.

Results: No significant differences in settling values were found between EHC and ITC. There were significant differences in the RTVs of EHC implants, but ITC implants showed no difference in RTV with different prosthetic retightening applications.

Conclusion: The retightening application affected the joint stability of EHC implants but did not affect the settlement and joint stability of ITC implants. Int J Prosthodont 2023;36:181-188. doi: 10.11607/ijp.6863.

Purpose: To determine the effect of scanning protocol, number of implants, and implant splinting on the accuracy of digital scanning in the edentulous arch.

Materials and methods: A resin-based model of an edentulous mandible with six implants was scanned with a coordinate measurement machine as a reference and then with two intraoral scanner (IOS) systems (Trios 3 and Primescan). Ten scans were taken per IOS for three experiments, and each scan was compared to the reference data to evaluate trueness and precision. Analysis involved measurement of linear and angular discrepanices using engineering software. In experiment 1, three scanning protocols were compared (curvilinear, zigzag, and half-arch). In experiment 2, three clinical situations were simulated (6 implants, 4 implants-short arch, and 4 implants-long arch). In experiment 3, the effect of implant splinting with a suture thread was measured. Normal distribution of data was examined with Shapiro-Wilk test. Levene test was used for equality of variance (α = .05). Statistical differences in distance and angular deviations were analyzed using Student t test or ANOVA with post hoc Tukey test (α = .05).

Results: The best results in terms of trueness and precision were obtained with a linear scanning protocol and six implants. The results were as follows: Trios 3: trueness = 52 μm/0.42 degrees, precision = 40 μm/0.26 degrees; Primescan: trueness = 24 μm/0.28 degrees, precision = 18 μm/0.27 degrees. The scanning protocol did not significantly affect distance or angular deviation accuracy. Trueness and precision significantly decreased with four implants using Primescan and TRIOS 3. Splinting implants negatively affected accuracy with both IOS devices.

Conclusion: Both IOS devices achieved clinically satisfying accuracy for distance (< 100 μm) and angular (< 0.5 degrees) deviations with six implants and a linear scanning protocol. With four implants, angular deviations sometimes differed between implants within the same group depending on the IOS and the clinical situation. Int J Prosthodont 2023;36:219-227. doi: 10.11607/ijp.7332.

Purpose: To evaluate oral health-related quality of life (OHRQoL) in patients with temporomandibular disorders (TMDs) involving masticatory muscle pain, disc displacement with reduction, or both and to determine the associations of these disorders with anxiety.

Materials and methods: This study consisted of 150 patients with TMDs and 50 healthy controls. Patients were diagnosed according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I and then divided into three diagnostic groups: masticatory muscle pain (group MP), disc displacement with reduction (group DD), or both (group MPDD). The participants completed the Oral Health Impact Profile-14 (OHIP-14) and Generalized Anxiety Disorder-7 (GAD-7) questionnaires for assessment of OHRQoL and anxiety, respectively. Statistical analyses were performed using Kruskal-Wallis test and Mann-Whitney U post hoc paired-comparison tests.

Results: A total of 121 of the patients (60.25%) were female and 79 (39.75%) were male, ranging from ages 18 to 68 years (mean age: 37.32 ± 13.62). Gender distribution, mean age, educational status, and occupational status were similar among groups. The OHIP-14 global and domain scores and distribution of GAD-7 levels were significantly different among groups (P < .001). For psychologic discomfort and disability domains, group MPDD statistically scored the highest, followed by group MP, group DD, and then the control group (P < .05). According to correlation analyses, there were positive correlations between the GAD-7 and all OHIP-14 scores (r = 0.438, P < .001) within group MPDD.

Conclusion: OHRQoL is negatively affected by TMDs and worsens as the severity of anxiety increases. Therefore, physical conditions and anxiety levels in TMD patients should be simultaneously considered for treatment and maintenance. Int J Prosthodont 2023;36:148-154. doi: 10.11607/ijp.7587.